A large variety of pigment compositions are known. For example, Patent Document No. 1 discloses a pigment composition containing 100 parts of an organic pigment and 1 to 15 parts of an aliphatic dicarboxylic acid having 1 to 8 carbon atoms. Patent Document No. 2 discloses a pigment composition containing 100 parts of an organic pigment and 1 to 15 parts of an aliphatic acid having 6 to 21 carbon atoms. In addition, a pigment composition which contains a self-condensate of an aliphatic acid having a hydroxyl group and an organic pigment is also well known. However, when a pigment dispersion used for an ink or a coating, is produced using such pigment compositions, there is a defect in that the fluidity and gloss are insufficient.
Patent Document No. 3 discloses a pigment composition containing an organic pigment and an ester compound produced by an aliphatic acid having a hydroxyl group and an aliphatic acid. The affinity to a dispersion medium is improved by converting a carboxylic acid into a compound having an ester bond. Thereby, not only can the ink fluidity be improved, but the gloss can also be improved, and a flushing time during ink production can also be reduced.    Patent Document No. 1: Japanese Unexamined Patent Application, First Publication No. H6-16986    Patent Document No. 2: Japanese Unexamined Patent Application, First Publication No. H6-16987    Patent Document No. 3: Japanese Unexamined Patent Application, First Publication No. H11-323238